diff --git a/tools/efivar.py b/tools/efivar.py new file mode 100755 index 0000000000..ebfcab2f0a --- /dev/null +++ b/tools/efivar.py @@ -0,0 +1,380 @@ +#!/usr/bin/env python3 +## SPDX-License-Identifier: GPL-2.0-only +# +# EFI variable store utilities. +# +# (c) 2020 Paulo Alcantara +# + +import os +import struct +import uuid +import time +import zlib +import argparse +from OpenSSL import crypto + +# U-Boot variable store format (version 1) +UBOOT_EFI_VAR_FILE_MAGIC = 0x0161566966456255 + +# UEFI variable attributes +EFI_VARIABLE_NON_VOLATILE = 0x1 +EFI_VARIABLE_BOOTSERVICE_ACCESS = 0x2 +EFI_VARIABLE_RUNTIME_ACCESS = 0x4 +EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS = 0x10 +EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS = 0x20 +EFI_VARIABLE_READ_ONLY = 1 << 31 +NV_BS = EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS +NV_BS_RT = NV_BS | EFI_VARIABLE_RUNTIME_ACCESS +NV_BS_RT_AT = NV_BS_RT | EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS +DEFAULT_VAR_ATTRS = NV_BS_RT + +# vendor GUIDs +EFI_GLOBAL_VARIABLE_GUID = '8be4df61-93ca-11d2-aa0d-00e098032b8c' +EFI_IMAGE_SECURITY_DATABASE_GUID = 'd719b2cb-3d3a-4596-a3bc-dad00e67656f' +EFI_CERT_TYPE_PKCS7_GUID = '4aafd29d-68df-49ee-8aa9-347d375665a7' +WIN_CERT_TYPE_EFI_GUID = 0x0ef1 +WIN_CERT_REVISION = 0x0200 + +var_attrs = { + 'NV': EFI_VARIABLE_NON_VOLATILE, + 'BS': EFI_VARIABLE_BOOTSERVICE_ACCESS, + 'RT': EFI_VARIABLE_RUNTIME_ACCESS, + 'AT': EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS, + 'RO': EFI_VARIABLE_READ_ONLY, + 'AW': EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS, +} + +var_guids = { + 'EFI_GLOBAL_VARIABLE_GUID': EFI_GLOBAL_VARIABLE_GUID, + 'EFI_IMAGE_SECURITY_DATABASE_GUID': EFI_IMAGE_SECURITY_DATABASE_GUID, +} + +class EfiStruct: + # struct efi_var_file + var_file_fmt = ' self.efi.var_file_size: + with open(self.infile, 'rb') as f: + buf = f.read() + self._check_header(buf) + self.ents = buf[self.efi.var_file_size:] + else: + self.ents = bytearray() + + def _check_header(self, buf): + hdr = struct.unpack_from(self.efi.var_file_fmt, buf, 0) + magic, crc32 = hdr[1], hdr[3] + + if magic != UBOOT_EFI_VAR_FILE_MAGIC: + print("err: invalid magic number: %s"%hex(magic)) + exit(1) + if crc32 != calc_crc32(buf[self.efi.var_file_size:]): + print("err: invalid crc32: %s"%hex(crc32)) + exit(1) + + def _get_var_name(self, buf): + name = '' + for i in range(0, len(buf) - 1, 2): + if not buf[i] and not buf[i+1]: + break + name += chr(buf[i]) + return ''.join([chr(x) for x in name.encode('utf_16_le') if x]), i + 2 + + def _next_var(self, offs=0): + size, attrs, time, guid = struct.unpack_from(self.efi.var_entry_fmt, self.ents, offs) + data_fmt = str(size)+"s" + offs += self.efi.var_entry_size + name, namelen = self._get_var_name(self.ents[offs:]) + offs += namelen + data = struct.unpack_from(data_fmt, self.ents, offs)[0] + # offset to next 8-byte aligned variable entry + offs = (offs + len(data) + 7) & ~7 + return EfiVariable(size, attrs, time, uuid.UUID(bytes_le=guid), name, data), offs + + def __iter__(self): + self.offs = 0 + return self + + def __next__(self): + if self.offs < len(self.ents): + var, noffs = self._next_var(self.offs) + self.offs = noffs + return var + else: + raise StopIteration + + def __len__(self): + return len(self.ents) + + def _set_var(self, guid, name_data, size, attrs, tsec): + ent = struct.pack(self.efi.var_entry_fmt, + size, + attrs, + tsec, + uuid.UUID(guid).bytes_le) + ent += name_data + self.ents += ent + + def del_var(self, guid, name, attrs): + offs = 0 + while offs < len(self.ents): + var, loffs = self._next_var(offs) + if var.name == name and str(var.guid): + if var.attrs != attrs: + print("err: attributes don't match") + exit(1) + self.ents = self.ents[:offs] + self.ents[loffs:] + return + offs = loffs + print("err: variable not found") + exit(1) + + def set_var(self, guid, name, data, size, attrs): + offs = 0 + while offs < len(self.ents): + var, loffs = self._next_var(offs) + if var.name == name and str(var.guid) == guid: + if var.attrs != attrs: + print("err: attributes don't match") + exit(1) + # make room for updating var + self.ents = self.ents[:offs] + self.ents[loffs:] + break + offs = loffs + + tsec = int(time.time()) if attrs & EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS else 0 + nd = name.encode('utf_16_le') + b"\x00\x00" + data + # U-Boot variable format requires the name + data blob to be 8-byte aligned + pad = ((len(nd) + 7) & ~7) - len(nd) + nd += bytes([0] * pad) + + return self._set_var(guid, nd, size, attrs, tsec) + + def save(self): + hdr = struct.pack(self.efi.var_file_fmt, + 0, + UBOOT_EFI_VAR_FILE_MAGIC, + len(self.ents) + self.efi.var_file_size, + calc_crc32(self.ents)) + + with open(self.infile, 'wb') as f: + f.write(hdr) + f.write(self.ents) + +def parse_attrs(attrs): + v = DEFAULT_VAR_ATTRS + if attrs: + v = 0 + for i in attrs.split(','): + v |= var_attrs[i.upper()] + return v + +def parse_data(val, vtype): + if not val or not vtype: + return None, 0 + fmt = { 'u8': '