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#!/usr/bin/env python3
#
# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: MIT
import os
import zlib
import base64
import tempfile
import crc32c
from .varstore import UEFIVar, UEFIVarStore
from .aws_v0 import UEFIVarStoreV0
from .aws_file import AWSVarStoreFile
class AWSUEFIVarStore(UEFIVarStore):
EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS = 0x20
AMZNUEFI = 0x494645554e5a4d41
def __init__(self, b64data: bytes):
super().__init__()
# Convert base64 to binary
file = tempfile.SpooledTemporaryFile()
file.write(base64.b64decode(b64data))
file.seek(0, os.SEEK_SET)
# Then wrap the binary file with our reader and start parsing
file = AWSVarStoreFile(file)
magic = file.read64()
if magic != self.AMZNUEFI:
raise Exception("Invalid magic. Expected AMZNUEFI. Found 0x%x" % magic)
crc32 = file.read32()
# Validate crc32c
location = file.file.tell()
comp_crc32 = crc32c.crc32(file.readall())
if (comp_crc32 != crc32):
raise Exception("Invalid checksum, please check you copied all data")
file.file.seek(location, os.SEEK_SET)
version = file.read32()
if version != 0:
raise Exception("Invalid version. Expected 0. Found 0x%x" % version)
# Grab the zlib data that's embedded and parse it
dec = zlib.decompressobj(0, zdict=UEFIVarStoreV0.dict)
raw_data = dec.decompress(file.readall())
raw_file = tempfile.SpooledTemporaryFile()
raw_file.write(raw_data)
raw_file.seek(0, os.SEEK_SET)
raw = AWSVarStoreFile(raw_file)
nr_entries = raw.read64()
for i in range(nr_entries):
name = raw.readstr()
data = raw.readdata()
guid = raw.readguid()
attr = raw.read32()
if attr & self.EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS:
timestamp = raw.readtimestamp()
if timestamp == self.EMPTY_TIMESTAMP:
timestamp = None
digest = raw.readdata()
if digest == self.EMPTY_DIGEST:
digest = None
self.vars.append(UEFIVar(name, data, guid, attr, timestamp, digest))
else:
self.vars.append(UEFIVar(name, data, guid, attr))
def __bytes__(self) -> bytes:
# Assemble the zlib compressed wrapped file
raw = AWSVarStoreFile(tempfile.SpooledTemporaryFile())
raw.write64(len(self.vars))
for var in self.vars:
raw.writestr(var.name)
raw.writedata(var.data)
raw.writeguid(var.guid)
raw.write32(var.attr)
if var.attr & self.EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS:
timestamp = var.timestamp
if timestamp is None:
timestamp = self.EMPTY_TIMESTAMP
digest = var.digest
if digest is None:
digest = self.EMPTY_DIGEST
raw.writetimestamp(timestamp)
raw.writedata(digest)
raw.file.seek(0, os.SEEK_SET)
enc = zlib.compressobj(9, zdict=UEFIVarStoreV0.dict)
zdata = enc.compress(raw.file.read()) + enc.flush()
# Create a full file with header + zdata
f = tempfile.SpooledTemporaryFile()
f = AWSVarStoreFile(f)
f.write64(self.AMZNUEFI)
f.write32(crc32c.crc32(int(0).to_bytes(4, byteorder='little') + zdata))
f.write32(0) # Version 0
f.write(zdata)
f.file.seek(0, os.SEEK_SET)
# Then write it out as base64 data
return base64.b64encode(f.file.read())
def __str__(self) -> str:
return self.__bytes__().decode('utf-8')