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Ghidra Import: Support virtual inheritance (#1071)

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* Implement/fix Ghidra imports for multiple and virtual inheritance

Unfortunately, the handling in Ghidra is still far from perfect. This is a good place to start, though.

* Support offsets in vbase pointers

* Support `this adjust`

* minor stylistic improvement

* Improvements to documentation

---------

Co-authored-by: jonschz <jonschz@users.noreply.github.com>
This commit is contained in:
jonschz
2024-07-30 19:02:15 +02:00
committed by GitHub
parent 1f251ff817
commit 412200ecbc
6 changed files with 549 additions and 72 deletions
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137
tools/ghidra_scripts/lego_util/function_importer.py
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@@ -10,6 +10,12 @@ from ghidra.program.model.listing import Function, Parameter
from ghidra.program.flatapi import FlatProgramAPI
from ghidra.program.model.listing import ParameterImpl
from ghidra.program.model.symbol import SourceType
from ghidra.program.model.data import (
TypeDef,
TypedefDataType,
Pointer,
ComponentOffsetSettingsDefinition,
)
from lego_util.pdb_extraction import (
PdbFunction,
@@ -17,12 +23,13 @@ from lego_util.pdb_extraction import (
CppStackSymbol,
)
from lego_util.ghidra_helper import (
add_pointer_type,
add_data_type_or_reuse_existing,
get_or_add_pointer_type,
get_ghidra_namespace,
sanitize_name,
)
from lego_util.exceptions import StackOffsetMismatchError
from lego_util.exceptions import StackOffsetMismatchError, Lego1Exception
from lego_util.type_importer import PdbTypeImporter
@@ -91,7 +98,10 @@ class PdbFunctionImporter:
if (
(not return_type_match)
and (self.return_type.getLength() > 4)
and (add_pointer_type(self.api, self.return_type) == ghidra_return_type)
and (
get_or_add_pointer_type(self.api, self.return_type)
== ghidra_return_type
)
and any(
param
for param in ghidra_function.getParameters()
@@ -103,19 +113,22 @@ class PdbFunctionImporter:
)
return_type_match = True
# match arguments: decide if thiscall or not
# match arguments: decide if thiscall or not, and whether the `this` type matches
thiscall_matches = (
self.signature.call_type == ghidra_function.getCallingConventionName()
)
ghidra_params_without_this = list(ghidra_function.getParameters())
if thiscall_matches and self.signature.call_type == "__thiscall":
this_argument = ghidra_params_without_this.pop(0)
thiscall_matches = self._this_type_match(this_argument)
if self.is_stub:
# We do not import the argument list for stubs, so it should be excluded in matches
args_match = True
elif thiscall_matches:
if self.signature.call_type == "__thiscall":
args_match = self._matches_thiscall_parameters(ghidra_function)
else:
args_match = self._matches_non_thiscall_parameters(ghidra_function)
args_match = self._parameter_lists_match(ghidra_params_without_this)
else:
args_match = False
@@ -136,16 +149,22 @@ class PdbFunctionImporter:
and args_match
)
def _matches_non_thiscall_parameters(self, ghidra_function: Function) -> bool:
return self._parameter_lists_match(ghidra_function.getParameters())
def _this_type_match(self, this_parameter: Parameter) -> bool:
if this_parameter.getName() != "this":
logger.info("Expected first argument to be `this` in __thiscall")
return False
def _matches_thiscall_parameters(self, ghidra_function: Function) -> bool:
ghidra_params = list(ghidra_function.getParameters())
if self.signature.this_adjust != 0:
# In this case, the `this` argument should be custom defined
if not isinstance(this_parameter.getDataType(), TypeDef):
logger.info(
"`this` argument is not a typedef while `this adjust` = %d",
self.signature.this_adjust,
)
return False
# We are not checking for the _correct_ `this` type here, which we could do in the future
# remove the `this` argument which we don't generate ourselves
ghidra_params.pop(0)
return self._parameter_lists_match(ghidra_params)
return True
def _parameter_lists_match(self, ghidra_params: "list[Parameter]") -> bool:
# Remove return storage pointer from comparison if present.
@@ -194,6 +213,25 @@ class PdbFunctionImporter:
def overwrite_ghidra_function(self, ghidra_function: Function):
"""Replace the function declaration in Ghidra by the one derived from C++."""
if ghidra_function.hasCustomVariableStorage():
# Unfortunately, calling `ghidra_function.setCustomVariableStorage(False)`
# leads to two `this` parameters. Therefore, we first need to remove all `this` parameters
# and then re-generate a new one
ghidra_function.replaceParameters(
Function.FunctionUpdateType.DYNAMIC_STORAGE_ALL_PARAMS, # this implicitly sets custom variable storage to False
True,
SourceType.USER_DEFINED,
[
param
for param in ghidra_function.getParameters()
if param.getName() != "this"
],
)
if ghidra_function.hasCustomVariableStorage():
raise Lego1Exception("Failed to disable custom variable storage.")
ghidra_function.setName(self.name, SourceType.USER_DEFINED)
ghidra_function.setParentNamespace(self.namespace)
ghidra_function.setReturnType(self.return_type, SourceType.USER_DEFINED)
@@ -203,16 +241,18 @@ class PdbFunctionImporter:
logger.debug(
"%s is a stub, skipping parameter import", self.get_full_name()
)
return
else:
ghidra_function.replaceParameters(
Function.FunctionUpdateType.DYNAMIC_STORAGE_ALL_PARAMS,
True, # force
SourceType.USER_DEFINED,
self.arguments,
)
self._import_parameter_names(ghidra_function)
ghidra_function.replaceParameters(
Function.FunctionUpdateType.DYNAMIC_STORAGE_ALL_PARAMS,
True, # force
SourceType.USER_DEFINED,
self.arguments,
)
self._import_parameter_names(ghidra_function)
# Special handling for `this adjust` and virtual inheritance
if self.signature.this_adjust != 0:
self._set_this_adjust(ghidra_function)
def _import_parameter_names(self, ghidra_function: Function):
# When we call `ghidra_function.replaceParameters`, Ghidra will generate the layout.
@@ -284,3 +324,50 @@ class PdbFunctionImporter:
),
None,
)
def _set_this_adjust(
self,
ghidra_function: Function,
):
"""
When `this adjust` is non-zero, the pointer type of `this` needs to be replaced by an offset version.
The offset can only be set on a typedef on the pointer. We also must enable custom storage so we can modify
the auto-generated `this` parameter.
"""
# Necessary in order to overwite the auto-generated `this`
ghidra_function.setCustomVariableStorage(True)
this_parameter = next(
(
param
for param in ghidra_function.getParameters()
if param.isRegisterVariable() and param.getName() == "this"
),
None,
)
if this_parameter is None:
logger.error(
"Failed to find `this` parameter in a function with `this adjust = %d`",
self.signature.this_adjust,
)
else:
current_ghidra_type = this_parameter.getDataType()
assert isinstance(current_ghidra_type, Pointer)
class_name = current_ghidra_type.getDataType().getName()
typedef_name = f"{class_name}PtrOffset0x{self.signature.this_adjust:x}"
typedef_ghidra_type = TypedefDataType(
current_ghidra_type.getCategoryPath(),
typedef_name,
current_ghidra_type,
)
ComponentOffsetSettingsDefinition.DEF.setValue(
typedef_ghidra_type.getDefaultSettings(), self.signature.this_adjust
)
typedef_ghidra_type = add_data_type_or_reuse_existing(
self.api, typedef_ghidra_type
)
this_parameter.setDataType(typedef_ghidra_type, SourceType.USER_DEFINED)