Files
volatility3/volatility/framework/symbols/intermed.py
T

245 lines
11 KiB
Python

import copy
import json
import logging
import lzma
import urllib.parse
from volatility import schemas
from volatility.framework import class_subclasses, constants, exceptions, interfaces, objects
from volatility.framework.exceptions import SymbolSpaceError
from volatility.framework.symbols import native
vollog = logging.getLogger(__name__)
# ## TODO
#
# All symbol tables should take a label to an object template
#
# Templates for subtypes etc should be looked up recursively just like anything else
# We therefore need a way to unroll rolled-up types
# Generate mangled names on the fly (prohibits external calling)
#
# Symbol list could be a dict with knowledge of its parent?
# Class split is arbitrary, it's an extension for developers
# Object template should contain both class and initial parameters
#
#
# *** Resolution should not happen in the resolve function
# It should only happen on access of contained types ***
#
# Recursive objects can be fixed by having caching the objects
# (however, they have to be built first!)
#
# Single hop resolution is probably the solution
# Could probably deal with it by having a property that caches
# for container types
#
def _construct_delegate_function(name, is_property = False):
def _delegate_function(self, *args, **kwargs):
if is_property:
return getattr(self._delegate, name)
return getattr(self._delegate, name)(*args, **kwargs)
if is_property:
return property(_delegate_function)
return _delegate_function
class IntermediateSymbolTable(interfaces.symbols.SymbolTableInterface):
def __init__(self, context, config_path, name, idd_filepath, native_types = None):
# Check there are no obvious errors
url = urllib.parse.urlparse(idd_filepath)
if url.scheme != 'file':
raise NotImplementedError(
"This scheme is not yet implement for the Intermediate Symbol Format: {}".format(url.scheme))
# Open the file and test the version
self._versions = dict([(x.version, x) for x in class_subclasses(ISFormatTable)])
if url.path.endswith('.xz'):
fp = lzma.open(url.path, 'rt')
else:
fp = open(url.path, "r")
json_object = json.load(fp)
fp.close()
# Validation is expensive, but we cache to store the hashes of successfully validated json objects
if not schemas.validate(json_object):
raise SymbolSpaceError("File does not pass version validation: {}".format(url.geturl()))
metadata = json_object.get('metadata', None)
# Determine the delegate or throw an exception
self._delegate = self._closest_version(metadata.get('format', "0.0.0"), self._versions)(context,
config_path,
name,
json_object,
native_types)
# Inherit
super().__init__(context, config_path, name, native_types or self._delegate.natives)
def _closest_version(self, version, versions):
"""Determines the highest suitable handler for specified version format"""
supported, age, revision = [int(x) for x in version.split(".")]
supported_versions = [x for x in versions.keys() if x[0] == supported and x[1] >= age]
if not supported_versions:
raise ValueError(
"No Intermediate Format interface versions support file interface version: {}".format(version))
return versions[max(supported_versions)]
symbols = _construct_delegate_function('symbols', True)
types = _construct_delegate_function('types', True)
get_type = _construct_delegate_function('get_type')
get_symbol = _construct_delegate_function('get_symbol')
get_type_class = _construct_delegate_function('get_type_class')
set_type_class = _construct_delegate_function('set_type_class')
del_type_class = _construct_delegate_function('del_type_class')
class ISFormatTable(interfaces.symbols.SymbolTableInterface):
"""Provide a base class to identify all subclasses"""
pass
class Version1Format(ISFormatTable):
"""Class for storing intermediate debugging data as objects and classes"""
current = 1
revision = 0
age = 1
version = (current - age, age, revision)
def __init__(self, context, config_path, name, json_object, native_types = None):
self._json_object = json_object
self._validate_json()
nt = native_types or self._get_natives()
super().__init__(context, config_path, name, nt)
self._overrides = {}
self._symbol_cache = None
def _get_natives(self):
"""Determines the appropriate native_types to use from the JSON data"""
classes = {"x64": native.x64NativeTable, "x86": native.x86NativeTable}
for nc in classes:
native_class = classes[nc]
for base_type in self._json_object['base_types']:
try:
if self._json_object['base_types'][base_type]['length'] != native_class.get_type(base_type).size:
break
except TypeError:
# TODO: determine whether we should give voids a size - We don't give voids a length, whereas microsoft seemingly do
pass
else:
vollog.debug("Choosing appropriate natives for symbol library: {}".format(nc))
return native_class.natives
# TODO: Check the format and make use of the other metadata
def _validate_json(self):
if (not 'user_types' in self._json_object or
not 'base_types' in self._json_object or
not 'metadata' in self._json_object or
not 'symbols' in self._json_object or
not 'enums' in self._json_object):
raise exceptions.SymbolSpaceError("Malformed JSON file provided")
def get_symbol(self, name):
"""Returns the location offset given by the symbol name"""
symbol = self._json_object['symbols'].get(name, None)
if not symbol:
raise KeyError("Unknown symbol: {}".format(name))
return interfaces.symbols.Symbol(name = name, address = symbol['address'])
@property
def symbols(self):
if not self._symbol_cache:
self._symbol_cache = [
interfaces.symbols.Symbol(name = x, address = self._json_object['symbols'][x]['address']) for
x in self._json_object['symbols']]
return self._symbol_cache
# TODO: Add the ability to add/remove/change symbols after creation, note that this should invalidate the cache
def get_type_class(self, name):
return self._overrides.get(name, objects.Struct)
def set_type_class(self, name, clazz):
if name not in self.types:
raise ValueError("Symbol type not in {} SymbolTable: {}".format(self.name, name))
self._overrides[name] = clazz
def del_type_class(self, name):
if name in self._overrides:
del self._overrides[name]
@property
def types(self):
"""Returns an iterator of the symbol names"""
return self._json_object.get('user_types', {})
def _interdict_to_template(self, dictionary):
"""Converts an intermediate format dict into an object template"""
if not dictionary:
raise exceptions.SymbolSpaceError("Invalid intermediate dictionary: {}".format(dictionary))
type_name = dictionary['kind']
if type_name == 'base':
type_name = dictionary['name']
if type_name in self.natives.types:
# The symbol is a native type
native_template = self.natives.get_type(type_name)
# Add specific additional parameters, etc
update = {}
if type_name == 'array':
update['count'] = dictionary['count']
update['subtype'] = self._interdict_to_template(dictionary['subtype'])
elif type_name == 'pointer':
update['subtype'] = self._interdict_to_template(dictionary['subtype'])
elif type_name == 'enum':
update = self._lookup_enum(dictionary['name'])
elif type_name == 'bitfield':
update = {'start_bit': dictionary['bit_position'], 'end_bit': dictionary['bit_length']}
update['subtype'] = self._interdict_to_template(dictionary['type'])
native_template.update_vol(**update) # pylint: disable=W0142
return native_template
# Otherwise
if dictionary['kind'] not in ['struct', 'union']:
raise exceptions.SymbolSpaceError("Unknown Intermediate format: {}".format(dictionary))
reference_name = dictionary['name']
if constants.BANG not in reference_name:
reference_name = self.name + constants.BANG + reference_name
return objects.templates.ReferenceTemplate(type_name = reference_name)
def _lookup_enum(self, name):
"""Looks up an enumeration and returns a dictionary of __init__ parameters for an Enum"""
lookup = self._json_object['enums'].get(name, None)
if not lookup:
raise exceptions.SymbolSpaceError("Unknown enumeration found: {}".format(name))
result = {"choices": copy.deepcopy(lookup['constants']),
"subtype": self.natives.get_type(lookup['base'])}
return result
def get_type(self, type_name):
"""Resolves an individual symbol"""
if constants.BANG in type_name:
raise exceptions.SymbolError("Symbol for a different table requested: {}".format(type_name))
if type_name not in self._json_object['user_types']:
raise exceptions.SymbolError("Unknown symbol: {}".format(type_name))
curdict = self._json_object['user_types'][type_name]
members = {}
for member_name in curdict['fields']:
interdict = curdict['fields'][member_name]
member = (interdict['offset'], self._interdict_to_template(interdict['type']))
members[member_name] = member
object_class = self.get_type_class(type_name)
return objects.templates.ObjectTemplate(type_name = self.name + constants.BANG + type_name,
object_class = object_class,
size = curdict['length'],
members = members)