2020-01-03 12:16:33 +00:00
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import struct
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from enum import Enum
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from typing import Any, List, Optional
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import click
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import construct as c
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import pyblake2
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from trezorlib import cosi, firmware
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SYM_OK = click.style("\u2714", fg="green")
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SYM_FAIL = click.style("\u274c", fg="red")
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class Status(Enum):
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VALID = click.style("VALID", fg="green", bold=True)
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INVALID = click.style("INVALID", fg="red", bold=True)
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MISSING = click.style("MISSING", fg="blue", bold=True)
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DEVEL = click.style("DEVEL", fg="red", bold=True)
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def is_ok(self):
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return self is Status.VALID or self is Status.DEVEL
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VHASH_DEVEL = bytes.fromhex(
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"c5b4d40cb76911392122c8d1c277937e49c69b2aaf818001ec5c7663fcce258f"
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)
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AnyFirmware = c.Struct(
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"vendor_header" / c.Optional(firmware.VendorHeader),
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"image" / c.Optional(firmware.FirmwareImage),
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)
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class ImageType(Enum):
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VENDOR_HEADER = 0
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BOOTLOADER = 1
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FIRMWARE = 2
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def _make_dev_keys(*key_bytes: bytes) -> List[bytes]:
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return [k * 32 for k in key_bytes]
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def compute_vhash(vendor_header):
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m = vendor_header.sig_m
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n = vendor_header.sig_n
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pubkeys = vendor_header.pubkeys
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h = pyblake2.blake2s()
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h.update(struct.pack("<BB", m, n))
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for i in range(8):
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if i < n:
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h.update(pubkeys[i])
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else:
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h.update(b"\x00" * 32)
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return h.digest()
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def all_zero(data: bytes) -> bool:
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return all(b == 0 for b in data)
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def _check_signature_any(
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header: c.Container, m: int, pubkeys: List[bytes], is_devel: bool
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) -> Optional[bool]:
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if all_zero(header.signature) and header.sigmask == 0:
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return Status.MISSING
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try:
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digest = firmware.header_digest(header)
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cosi.verify(header.signature, digest, m, pubkeys, header.sigmask)
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return Status.VALID if not is_devel else Status.DEVEL
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except Exception:
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return Status.INVALID
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# ====================== formatting functions ====================
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class LiteralStr(str):
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pass
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def _format_container(
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pb: c.Container,
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indent: int = 0,
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sep: str = " " * 4,
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truncate_after: Optional[int] = 64,
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truncate_to: Optional[int] = 32,
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) -> str:
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def mostly_printable(bytes: bytes) -> bool:
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if not bytes:
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return True
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printable = sum(1 for byte in bytes if 0x20 <= byte <= 0x7E)
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return printable / len(bytes) > 0.8
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def pformat(value: Any, indent: int) -> str:
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level = sep * indent
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leadin = sep * (indent + 1)
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if isinstance(value, LiteralStr):
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return value
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if isinstance(value, list):
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# short list of simple values
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if not value or isinstance(value, (int, bool, Enum)):
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return repr(value)
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# long list, one line per entry
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lines = ["[", level + "]"]
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lines[1:1] = [leadin + pformat(x, indent + 1) for x in value]
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return "\n".join(lines)
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if isinstance(value, dict):
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lines = ["{"]
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for key, val in value.items():
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if key.startswith("_"):
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continue
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if val is None or val == []:
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continue
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lines.append(leadin + key + ": " + pformat(val, indent + 1))
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lines.append(level + "}")
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return "\n".join(lines)
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if isinstance(value, (bytes, bytearray)):
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length = len(value)
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suffix = ""
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if truncate_after and length > truncate_after:
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suffix = "..."
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value = value[: truncate_to or 0]
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if mostly_printable(value):
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output = repr(value)
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else:
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output = value.hex()
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return "{} bytes {}{}".format(length, output, suffix)
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if isinstance(value, Enum):
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return str(value)
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return repr(value)
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return pformat(pb, indent)
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def _format_version(version: c.Container) -> str:
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version_str = ".".join(
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str(version[k]) for k in ("major", "minor", "patch") if k in version
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)
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if "build" in version:
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2020-01-21 16:20:45 +00:00
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version_str += " build {}".format(version.build)
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2020-01-03 12:16:33 +00:00
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return version_str
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# =========================== functionality implementations ===============
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class SignableImage:
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NAME = "Unrecognized image"
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BIP32_INDEX = None
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DEV_KEYS = []
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DEV_KEY_SIGMASK = 0b11
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def __init__(self, fw: c.Container) -> None:
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self.fw = fw
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self.header = None
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self.public_keys = None
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self.sigs_required = firmware.V2_SIGS_REQUIRED
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def digest(self) -> bytes:
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return firmware.header_digest(self.header)
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def check_signature(self) -> Status:
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raise NotImplementedError
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def rehash(self) -> None:
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2020-01-03 15:43:44 +00:00
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pass
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2020-01-03 12:16:33 +00:00
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def insert_signature(self, signature: bytes, sigmask: int) -> None:
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self.header.signature = signature
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self.header.sigmask = sigmask
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def dump(self) -> bytes:
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return AnyFirmware.build(self.fw)
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def format(self, verbose: bool) -> str:
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return _format_container(self.fw)
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class VendorHeader(SignableImage):
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NAME = "vendorheader"
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BIP32_INDEX = 1
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DEV_KEYS = _make_dev_keys(b"\x44", b"\x45")
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def __init__(self, fw):
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super().__init__(fw)
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self.header = fw.vendor_header
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self.public_keys = firmware.V2_BOOTLOADER_KEYS
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def check_signature(self) -> Status:
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return _check_signature_any(
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self.header, self.sigs_required, self.public_keys, False
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)
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def _format(self, terse: bool) -> str:
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vh = self.fw.vendor_header
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if not terse:
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vhash = compute_vhash(vh)
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output = [
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"Vendor Header " + _format_container(vh),
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2020-01-21 16:20:45 +00:00
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"Pubkey bundle hash: {}".format(vhash.hex()),
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2020-01-03 12:16:33 +00:00
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]
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else:
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output = [
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"Vendor Header for {vendor} version {version} ({size} bytes)".format(
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vendor=click.style(vh.text, bold=True),
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version=_format_version(vh.version),
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size=vh.header_len,
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),
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]
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fingerprint = firmware.header_digest(vh)
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if not terse:
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2020-01-21 16:20:45 +00:00
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output.append(
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"Fingerprint: {}".format(click.style(fingerprint.hex(), bold=True))
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)
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2020-01-03 12:16:33 +00:00
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sig_status = self.check_signature()
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sym = SYM_OK if sig_status.is_ok() else SYM_FAIL
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2020-01-21 16:20:45 +00:00
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output.append("{} Signature is {}".format(sym, sig_status.value))
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2020-01-03 12:16:33 +00:00
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return "\n".join(output)
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def format(self, verbose: bool = False) -> str:
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return self._format(terse=False)
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class BinImage(SignableImage):
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def __init__(self, fw):
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super().__init__(fw)
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self.header = self.fw.image.header
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self.code_hashes = firmware.calculate_code_hashes(
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self.fw.image.code, self.fw.image._code_offset
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)
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self.digest_header = self.header.copy()
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self.digest_header.hashes = self.code_hashes
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def insert_signature(self, signature: bytes, sigmask: int) -> None:
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super().insert_signature(signature, sigmask)
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self.digest_header.signature = signature
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self.digest_header.sigmask = sigmask
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def digest(self) -> bytes:
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return firmware.header_digest(self.digest_header)
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def rehash(self):
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self.header.hashes = self.code_hashes
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def format(self, verbose: bool = False) -> str:
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header_out = self.header.copy()
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if not verbose:
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for key in self.header:
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if key.startswith("v1"):
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del header_out[key]
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if "version" in key:
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header_out[key] = LiteralStr(_format_version(self.header[key]))
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all_ok = SYM_OK
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hash_status = Status.VALID
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sig_status = Status.VALID
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hashes_out = []
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for expected, actual in zip(self.header.hashes, self.code_hashes):
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status = SYM_OK if expected == actual else SYM_FAIL
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2020-01-21 16:20:45 +00:00
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hashes_out.append(LiteralStr("{} {}".format(status, expected.hex())))
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2020-01-03 12:16:33 +00:00
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if all(all_zero(h) for h in self.header.hashes):
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hash_status = Status.MISSING
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elif self.header.hashes != self.code_hashes:
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hash_status = Status.INVALID
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else:
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hash_status = Status.VALID
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header_out["hashes"] = hashes_out
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sig_status = self.check_signature()
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all_ok = SYM_OK if hash_status.is_ok() and sig_status.is_ok() else SYM_FAIL
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output = [
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"Firmware Header " + _format_container(header_out),
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2020-01-21 16:20:45 +00:00
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"Fingerprint: {}".format(click.style(self.digest().hex(), bold=True)),
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"{} Signature is {}, hashes are {}".format(
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all_ok, sig_status.value, hash_status.value
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),
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2020-01-03 12:16:33 +00:00
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]
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return "\n".join(output)
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class FirmwareImage(BinImage):
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NAME = "firmware"
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BIP32_INDEX = 2
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DEV_KEYS = _make_dev_keys(b"\x47", b"\x48")
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def __init__(self, fw: c.Container) -> None:
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super().__init__(fw)
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self.public_keys = fw.vendor_header.pubkeys
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self.sigs_required = fw.vendor_header.sig_m
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def check_signature(self) -> Status:
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vhash = compute_vhash(self.fw.vendor_header)
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return _check_signature_any(
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self.digest_header,
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self.sigs_required,
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self.public_keys,
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vhash == VHASH_DEVEL,
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)
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def format(self, verbose: bool = False) -> str:
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return (
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VendorHeader(self.fw)._format(terse=not verbose)
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+ "\n"
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+ super().format(verbose)
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)
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class BootloaderImage(BinImage):
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NAME = "bootloader"
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BIP32_INDEX = 0
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DEV_KEYS = _make_dev_keys(b"\x41", b"\x42")
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def __init__(self, fw):
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super().__init__(fw)
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self._identify_dev_keys()
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def insert_signature(self, signature: bytes, sigmask: int) -> None:
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super().insert_signature(signature, sigmask)
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self._identify_dev_keys()
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def _identify_dev_keys(self):
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# try checking signature with dev keys first
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self.public_keys = firmware.V2_BOARDLOADER_DEV_KEYS
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if not self.check_signature().is_ok():
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# validation with dev keys failed, use production keys
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self.public_keys = firmware.V2_BOARDLOADER_KEYS
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def check_signature(self) -> Status:
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return _check_signature_any(
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self.header,
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self.sigs_required,
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self.public_keys,
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self.public_keys == firmware.V2_BOARDLOADER_DEV_KEYS,
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)
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def parse_image(image: bytes):
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fw = AnyFirmware.parse(image)
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if fw.vendor_header and not fw.image:
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return VendorHeader(fw)
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if (
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not fw.vendor_header
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and fw.image
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and fw.image.header.magic == firmware.HeaderType.BOOTLOADER
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):
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return BootloaderImage(fw)
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if (
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fw.vendor_header
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and fw.image
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and fw.image.header.magic == firmware.HeaderType.FIRMWARE
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):
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return FirmwareImage(fw)
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raise ValueError("Unrecognized image type")
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