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trezor-firmware/core/embed/firmware/bootloader_hashes.py
2023-11-08 15:39:24 +01:00

104 lines
2.8 KiB
Python
Executable File

#!/usr/bin/env python3
from pathlib import Path
from hashlib import blake2s
from trezorlib.firmware.core import FirmwareImage
ALIGNED_SIZE = 128 * 1024
HERE = Path(__file__).parent
BOOTLOADERS = HERE / "bootloaders"
BL_CHECK = HERE / "bl_check.c"
BL_CHECK_AUTO_BEGIN = "// --- BEGIN GENERATED BOOTLOADER SECTION ---\n"
BL_CHECK_AUTO_END = "// --- END GENERATED BOOTLOADER SECTION ---\n"
PATTERN = """\
// {name} version {version}
#define BOOTLOADER_{suffix}_00 {{{bytes_00}}}
#define BOOTLOADER_{suffix}_FF {{{bytes_ff}}}
"""
def aligned_digest(data: bytes, padding: bytes) -> bytes:
"""Calculate digest of data, aligned to ALIGNED_SIZE with
the specified padding.
Firmware needs to check the bootloader against a digest padded either by 0xff
(unwritten NOR-flash byte) or 0x00 (explicitly cleared byte).
"""
if len(data) > ALIGNED_SIZE:
raise ValueError(fn, "too big")
assert len(padding) == 1
digest_data = data + padding * (ALIGNED_SIZE - len(data))
assert len(digest_data) == ALIGNED_SIZE
return blake2s(digest_data).digest()
def to_uint_array(data: bytes) -> str:
"""Convert bytes to C array of uint8_t, like so:
>>> to_uint_array(b"\\x00\\x01\\x02")
"{0x00, 0x01, 0x02}"
"""
return ", ".join([f"0x{i:02x}" for i in data])
def bootloader_str(file: Path) -> str:
"""From a given file, generate the relevant C definition strings from PATTERN.
Calculates the two padded hashes, one with 0x00 and the other 0xFF, and returns
a string suitable for writing into bl_check.c.
"""
data = file.read_bytes()
suffix = file.stem[len("bootloader_") :].upper()
bytes_00 = to_uint_array(aligned_digest(data, b"\x00"))
bytes_ff = to_uint_array(aligned_digest(data, b"\xff"))
try:
bl = FirmwareImage.parse(data)
version_str = ".".join(str(x) for x in bl.header.version)
except Exception:
version_str = "<unknown>"
return PATTERN.format(
name=file.name,
version=version_str,
suffix=suffix,
bytes_00=bytes_00,
bytes_ff=bytes_ff,
)
def main():
bl_check_new = []
with open(BL_CHECK) as f:
# read up to auto-begin
for line in f:
bl_check_new.append(line)
if line == BL_CHECK_AUTO_BEGIN:
break
# write bootloader definitions
for file in sorted(BOOTLOADERS.glob("bootloader*.bin")):
bl_check_new.append(bootloader_str(file))
# consume up to auto-end
for line in f:
if line == BL_CHECK_AUTO_END:
bl_check_new.append(line)
break
# read the rest
bl_check_new.extend(f)
# write the file
BL_CHECK.write_text("".join(bl_check_new))
if __name__ == "__main__":
main()