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"""Functionality to execute native programs and collect snapshots via lldb."""
import re
import sys
import lldb
from typing import Callable
# TODO: The debugger callback is currently specific to a single architexture.
# We should make it generic.
from arch import x86
from utils import print_separator
verbose = False
class DebuggerCallback:
"""At every breakpoint, writes register contents to a stream."""
def __init__(self, ostream=sys.stdout):
self.stream = ostream
self.regex = re.compile('(' + '|'.join(x86.regnames) + ')$')
@staticmethod
def parse_flags(flag_reg: int):
flags = {'ZF': 0,
'CF': 0,
'OF': 0,
'SF': 0,
'PF': 0,
'DF': 0}
# CF (Carry flag) Bit 0
# PF (Parity flag) Bit 2
# ZF (Zero flag) Bit 6
# SF (Sign flag) Bit 7
# TF (Trap flag) Bit 8
# IF (Interrupt enable flag) Bit 9
# DF (Direction flag) Bit 10
# OF (Overflow flag) Bit 11
flags['CF'] = int(0 != flag_reg & 1)
flags['ZF'] = int(0 != flag_reg & (1 << 6))
flags['OF'] = int(0 != flag_reg & (1 << 11))
flags['SF'] = int(0 != flag_reg & (1 << 7))
flags['DF'] = int(0 != flag_reg & (1 << 10))
flags['PF'] = int(0 != flag_reg & (1 << 1))
return flags
def print_regs(self, frame):
for reg in frame.GetRegisters():
for sub_reg in reg:
match = self.regex.match(sub_reg.GetName().upper())
if match and match.group() == 'RFLAGS':
flags = DebuggerCallback.parse_flags(int(sub_reg.GetValue(),
base=16))
for flag in flags:
print(f'flag {flag}:\t{hex(flags[flag])}',
file=self.stream)
elif match:
print(f"{sub_reg.GetName().upper()}:\t\t {hex(int(sub_reg.GetValue(), base=16))}",
file=self.stream)
def print_stack(self, frame, element_count: int):
first = True
for i in range(element_count):
addr = frame.GetSP() + i * frame.GetThread().GetProcess().GetAddressByteSize()
error = lldb.SBError()
stack_value = int(frame.GetThread().GetProcess().ReadPointerFromMemory(addr, error))
if error.Success() and not first:
print(f'{hex(stack_value)}', file=self.stream)
elif error.Success():
print(f'{hex(stack_value)}\t\t<- rsp', file=self.stream)
else:
print(f"Error reading memory at address 0x{addr:x}",
file=self.stream)
first=False
def __call__(self, frame):
pc = frame.GetPC()
print_separator('=', stream=self.stream, count=20)
print(f'INVOKE PC={hex(pc)}', file=self.stream)
print_separator('=', stream=self.stream, count=20)
print("Register values:", file=self.stream)
self.print_regs(frame)
print_separator(stream=self.stream)
print("STACK:", file=self.stream)
self.print_stack(frame, 20)
class Debugger:
def __init__(self, program):
self.debugger = lldb.SBDebugger.Create()
self.debugger.SetAsync(False)
self.target = self.debugger.CreateTargetWithFileAndArch(program,
lldb.LLDB_ARCH_DEFAULT)
self.module = self.target.FindModule(self.target.GetExecutable())
self.interpreter = self.debugger.GetCommandInterpreter()
def set_breakpoint_by_addr(self, address: int):
command = f"b -a {address} -s {self.module.GetFileSpec().GetFilename()}"
result = lldb.SBCommandReturnObject()
self.interpreter.HandleCommand(command, result)
if verbose:
print(f'Set breakpoint at address {hex(address)}')
def get_breakpoints_count(self):
return self.target.GetNumBreakpoints()
def execute(self, callback: Callable):
error = lldb.SBError()
listener = self.debugger.GetListener()
process = self.target.Launch(listener, None, None, None, None, None, None, 0,
True, error)
# Check if the process has launched successfully
if process.IsValid():
print(f'Launched process: {process}')
else:
print('Failed to launch process', file=sys.stderr)
while True:
state = process.GetState()
if state == lldb.eStateStopped:
for thread in process:
callback(thread.GetFrameAtIndex(0))
process.Continue()
if state == lldb.eStateExited:
break
self.debugger.Terminate()
print(f'Process state: {process.GetState()}')
print('Program output:')
print(process.GetSTDOUT(1024))
print(process.GetSTDERR(1024))
class ListWriter:
def __init__(self):
self.data = []
def write(self, s):
self.data.append(s)
def __str__(self):
return "".join(self.data)
def run_native_execution(oracle_program: str, breakpoints: set[int]):
"""Gather snapshots from a native execution via an external debugger.
:param oracle_program: Program to execute.
:param breakpoints: List of addresses at which to break and record the
program's state.
:return: A textual log of the program's execution in arancini's log format.
"""
debugger = Debugger(oracle_program)
writer = ListWriter()
# Set breakpoints
for address in breakpoints:
debugger.set_breakpoint_by_addr(address)
assert(debugger.get_breakpoints_count() == len(breakpoints))
# Execute the native program
debugger.execute(DebuggerCallback(writer))
return writer.data
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